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 60 water, milk, oil, wine, ink, etc., or in any of these with solid bodies, such as nitre and salt, dissolved in them. He points out that the effect both on the plant and on the liquid should be noted. The solid body should be weighed before solution, and then, after the experiment is over, the liquid should be evaporated and the solid again weighed.

Another instance in which he suggested an experiment, apparently without carrying it out, was in relation to the movements of the stems of non-climbing plants. He seems to have anticipated the nineteenth century discovery of nutation amongst plants other than climbers, though he stopped short of actually proving it. In his account of the Motions of Trunks he remarks, "The Convolution of Plants, hath been observed only in those that Climb. But it seems probable, that many others do also wind;…Whether it be so, or not the Experiment may easily be made by tying a Thred upon any of the Branches; setting down the respect it then hath to any Quarter in the Heavens: for, if it shall appear in two or three Months, to have changed its Situation towards some other Quarter; it is certain proof hereof." He noticed that some plants twine "by South from East to West" and others "from West to East," and attributed this to their being respectively under the influence of the sun and the moon.

Whenever Grew's notions of plant physiology depended upon chemistry, they became, according to our modern ideas, extremely difficult to follow. He held, among many other curious beliefs, that salts obtained from any plant have a tendency to crystallise out in a form resembling that plant, and adds, as an illustration from the animal world, "though I have not seen it my self, yet I have been told by one that doth not use to phancy things, that the Volatile Salt of Vipers, will figure it self into the semblance of little Vipers."

The mystical belief that characteristic "principles" permeate all things, finds expression in his idea that the "frost flowers," sometimes to be seen on a window pane, are evidence that the air is impregnated with "Vegetable Principles." Another fact, which he brings forward in support of the same view, is that the ground or water, when exposed for some time to air,